aggregate risk. We argue that interactions between the two risks are important for this question. One is a direct interaction in … the form of a countercyclical variance of idiosyncratic income risk. The other indirectly emerges over a household's life …-cycle because retirement savings contain the history of idiosyncratic and aggregate shocks. We show that this leads to risk …

facing uninsurable idiosyncratic labor income risk. The Ramsey government internalizes the general equilibrium feedback of … optimal aggregate saving rate is independent of income risk. The optimal time-invariant tax on capital is increasing in income … risk. Its sign depends on the extent of risk and on the Pareto weight of future generations. If the Ramsey tax rate that …

productivity and aggregate business cycle risk. We show analytically that the whole welfare benefit from joint insurance against … both risks is greater than the sum of benefits from insurance against the isolated risk components. One reason is the … convexity of the welfare gain in total risk. The other reason is a direct risk interaction which amplifies the utility losses …